Research and Engineering Application of Salt Erosion Resistance of Magnesium Oxychloride Cement Concrete

Chang, Chenggong; An, Lingyun; Zheng, Weixin; Wen, Jing; Dong, Jinmei; Yan, Fengyun; Xiao, Xueying

doi:10.3390/ma14247880

Cited by 11 publications

(6 citation statements)

References 20 publications

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“…It can be observed Figure 3 that the compressive strength of the MOC slurry sample that was steeped fo is 83.7 MPa, but with the extension of soaking time, the compressive strength of the M sample gradually decreases, and the reduced extent is much larger. Compared wit compressive strength of the MOC sample before soaking (0 h), the compressive stre of the sample after immersion for 6 h decreased by 52.2%, and it declined by nearly after 12 h. When the immersion time was further extended to 72 h, the compre strength was only 16.1% of what it was before immersion (0 h). After immersing for 1 the compressive strength of the sample is as low as 8.6 MPa.…”

Section: Compressive Strength Analysesmentioning

confidence: 85%

“…Since 1957, scientists have carried out a large number of studies on the development of potash fertilizer and its applications. Now, Materials 2023, 16, 5924 2 of 13 Qarhan Salt Lake is China's largest potash production base. However, there are significant quantities of bischofite accumulating in Qarhan Salt Lake after years of potassium extraction and production, forming "magnesium damage."…”

Section: Introductionmentioning

confidence: 99%

“…Nibras Y. Alani et al [15] investigated the performance of SCC containing nano clay at elevated temperatures and exposed to a MgSO 4 attack, and pointed out that the nano clay incorporating SCC specimens possessed higher durability properties. With respect to MOC, so far, the effects of a high salt environment, high heat environment, dry-wet cyclic environment and long-term indoor environment on the deterioration properties of MOC materials have also been reported [16][17][18][19]. However, if MOC materials are exposed to an environment with chemical substances, such as the alkaline environment of a production workshop, they may be damaged by chemical erosion.…”

Section: Introductionmentioning

confidence: 99%

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Study on the Deterioration Mechanism of Magnesium Oxychloride Cement under an Alkaline Environment

An,

Chang,

Yan

et al. 2023

Materials

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The deterioration process and deterioration mechanism of magnesium oxychloride cement (MOC) in an alkaline environment were studied using a scanning electron microscope (SEM), an X-ray diffractometer (XRD), a Fourier transform infrared spectrometer (FT-IR) and a micro-electro-hydraulic servo pressure testing machine to investigate the effects of soaking time in 10 wt.% NaOH solution on the macro- and micro-morphology, phase composition and compressive strength of MOC samples. The results show that the deterioration of MOC samples under an alkaline environment is mainly caused by the alkaline environment providing more OH− ions, which can react with 5Mg(OH)2·MgCl2·8H2O (P 5) in the sample. The resulting reaction gives rise to a faster decomposition of 5Mg(OH)2·MgCl2·8H2O (P 5) and a substantial reduction in the strength of the sample, and finally leads to a gradual deterioration of MOC samples. Meanwhile, immersion time exhibits a significant effect on MOC samples. The extension of immersion time coincides with more OH− ions entering the sample, and the greater presence of OH ions increases the likelihood that more P 5 will produce a hydrolysis reaction, further resulting in the increased deterioration of the sample. After soaking for 6 h in alkaline media, the main phase composition of the surface layer of an MOC sample changes to MgO and Mg(OH)2, and its microscopic morphology is also dominated by round sheets, giving rise to a sharp decrease in its compressive strength (52.2%). When the immersion time is prolonged to 72 h, OH− ions have already immersed into the inner core of the sample, causing the disappearance of P 5 from the whole sample. At the same time, both the surface and inner core of the sample exhibit a disc-shaped morphology, and chalking phenomena also appear on the surface of the sample. This reduces the compressive strength of the sample to 13.5 MPa, only 20% of its compressive strength in water. The compressive strength of the sample after 120 h of immersion is as low as 8.6 MPa, which is lower than that of the sample dipped in water for 21 days (9.5 MPa). As a result, the MOC samples studied in alkaline environments exhibit a faster deterioration rate, mainly because of a faster hydrolysis reaction by P 5, caused by more OH− ions.

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Section: Compressive Strength Analysesmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Study on the Deterioration Mechanism of Magnesium Oxychloride Cement under an Alkaline Environment

An,

Chang,

Yan

et al. 2023

Materials

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“…With the rapid development of materials science, magnesium-based cementitious materials have become an indispensable primary material in the building materials industry in recent years. 1,2 Magnesium cement is an airhardening cementitious material mainly made of MgO, with a simple production process, many excellent physical and mechanical properties, and unique engineering properties. 3,4 Magnesium oxychloride cement is a mixture of MgCl 2 , MgO, and H 2 O in a certain proportion, which is fully hydrated to form an air-hardening cementitious material mainly composed of a Mg(OH) 2 • b MgCl 2 • c H 2 O.…”

Section: Introductionmentioning

confidence: 99%

Ratio Optimization of Magnesium Oxychloride Cement and Improvement of Its Water Resistance Based on Response Surface Methodology

Junfang Fu,

Rongyao Chen

2024

SCE

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Magnesium oxychloride has excellent early strength, lightweight and environmentally friendly properties, and excellent application value. However, insufficient water resistance affects its engineering application. This paper uses fly ash to improve the water resistance of magnesium oxychloride cement (MOC). The response surface method was used to optimize the ratio of magnesium oxychloride cement. The influence of fly ash content, magnesium oxychloride cement ratio, and their interaction on the water resistance of magnesium oxychloride cement was studied using a response surface experiment. The fly ash content and magnesium oxychloride cement ratio were optimized to form magnesium oxychloride cement with good water-resistance. The experimental results show that the fitting efficiency of the response surface model is R2 = 0.9951; the model reflects the relationship between the factors of magnesium oxychloride cement and water resistance well. The magnesium oxychloride cement has a maximum softening coefficient of 0.898 when the amount of fly ash added is 21.94%, and the molar ratio of magnesium oxychloride cement is 11.49: 1:11.77. The magnesium oxychloride cement has good water resistance by optimizing the ratio based on external fly ash and response surface methodology. The study provides a reference for improving the water resistance of magnesium oxychloride cement.

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“…However, once a fire occurs, the temperature of a room can reach more than 400 • C. Furthermore, in accordance with the standard of "Code for Fire Protection in Building Design" (GB50016-2006), magnesium cement flue should be non-combustible bodies with a fire resistance rating of not less than 1.00 h. Therefore, it is important to study the high-temperature performance of magnesium oxychloride cement. At present, most scholarly research has mainly focused on the fields of water resistance [13][14][15][16][17][18] and composite functional materials [19][20][21][22][23], and there is a lack of reports on the application of magnesium oxychloride cement under the high-temperature conditions or of the impact of high temperature on its properties.…”

Section: Introductionmentioning

confidence: 99%

Effect of Calcination Temperature on Mechanical Properties of Magnesium Oxychloride Cement

Chang

Lin

et al. 2022

Materials

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In order to make full use of magnesium chloride resources, the development and utilisation of magnesium oxychloride cement have become an ecological and economic goal. Thus far, however, investigations into the effects on these cements of high temperatures are lacking. Herein, magnesium oxychloride cement was calcinated at various temperatures and the effects of calcination temperature on microstructure, phase composition, flexural strength, and compressive strength were studied by scanning electron microscopy, X-ray diffraction, and compression testing. The mechanical properties varied strongly with calcination temperature. Before calcination, magnesium oxychloride cement has a needle-like micromorphology and includes Mg(OH)2 gel and a trace amount of gel water as well as 5 Mg(OH)2·MgCl2·8H2O, which together provide its mechanical properties (flexural strength, 18.4 MPa; compressive strength, and 113.3 MPa). After calcination at 100 °C, the gel water is volatilised and the flexural strength is decreased by 57.07% but there is no significant change in the compressive strength. Calcination at 400 °C results in the magnesium oxychloride cement becoming fibrous and mainly consisting of Mg(OH)2 gel, which helps to maintain its high compressive strength (65.7 MPa). When the calcination temperature is 450 °C, the microstructure becomes powdery, the cement is mainly composed of MgO, and the flexural and compressive strengths are completely lost.

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Research and Engineering Application of Salt Erosion Resistance of Magnesium Oxychloride Cement Concrete

Cited by 11 publications

References 20 publications

Study on the Deterioration Mechanism of Magnesium Oxychloride Cement under an Alkaline Environment

Study on the Deterioration Mechanism of Magnesium Oxychloride Cement under an Alkaline Environment

Ratio Optimization of Magnesium Oxychloride Cement and Improvement of Its Water Resistance Based on Response Surface Methodology

Effect of Calcination Temperature on Mechanical Properties of Magnesium Oxychloride Cement

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